Fuel cells are electrochemical devices that convert chemical energy directly into electric energy. So long as a fuel, such as oxygen, is supplied to the electrodes, electric energy and some heat are produced. The reactants (e.g., fuel and oxygen) flow into the fuel cell, the reaction products (e.g., water) flow out of the cell, and the electrolyte medium remains in the fuel cell. Fuel cells find application in power stations for on-site power generation, automotive industry, transportation, mobile communications, and the like.